JP2011217480A - Control system of superconducting motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a control system of a superconducting motor which can enhance the efficiency of the superconducting motor by preventing the generation of a waste AC loss caused by a drift, in a device of an automobile or the like which employs the superconducting motor.SOLUTION: In the control system S of the superconducting motor 1, the superconducting motor includes a coil to which a plurality of windings are connected in parallel or a plurality of coils which are connected in parallel with one another, idling detection means S1, S2, S3 and S5 which detect the idling of the superconducting motor, and a control means 4 which can control a current value for driving the superconducting motor 1 according to an output of the idling detection means.

Description

  The present invention relates to a superconducting motor control system. More specifically, in a superconducting motor including a plurality of windings connected in parallel, or a plurality of coils connected in parallel, a superconducting motor control system capable of reducing AC loss and increasing efficiency. About.

  A superconducting motor provided with a superconducting coil has a very low coil electrical resistance, so that it has high energy efficiency and can obtain a large torque by flowing a large current. Further, since the cross-sectional area of the coil can be reduced as compared with the conventional copper wire, the motor can be reduced in size. For this reason, various uses have been developed as a power source for industrial machines as well as motors for driving automobiles.

  In order to realize a superconducting state in the superconducting coil, it is necessary to cool the coil temperature to at least the superconducting critical temperature. Even when the superconducting coil is cooled and a superconducting state can be realized, when an alternating current is passed through the coil, an alternating current loss due to a varying magnetic field occurs. The AC loss may decrease the efficiency of the motor, further increase the temperature of the coil, and hinder the superconducting state of the coil. Various methods have been proposed to reduce the AC loss.

Further, as a problem when using a superconducting coil, when a coil is formed by winding a plurality of windings connected in parallel, a drift phenomenon in which no current flows uniformly through these windings tends to occur. In particular, in a superconducting coil, a large current is often passed, and the drift becomes large and the coil temperature rises locally, leading to a large loss.

JP-A-9-180552

  The AC loss is obtained by adding a hysteresis loss due to a change in magnetic flux and a loss (coupling loss) due to an induced current flowing in a metal portion between filaments inside the wire. In addition, the ratio of the hysteresis loss is large, and this hysteresis loss is approximately proportional to the square of the magnetic flux density, and the magnetic flux density is proportional to the current value flowing through the coil. Therefore, the increase in the current value itself leads to a large AC loss.

  In addition, in a superconducting motor including a plurality of windings connected in parallel, or a plurality of coils connected in parallel, each winding or each coil has a difference between inductances. It is known that there is a drift in which the value of the flowing current is greatly biased between the parallel coils. When the motor is driven in a no-load idling state, a counter electromotive voltage is generated, so that current does not flow so much and power consumption is not large. However, in the no-load state, drift occurs between the parallel windings or between the parallel coils, and this current increases the AC loss, thereby reducing the efficiency of the superconducting motor. For example, a motor for driving an automobile has a problem that the above loss occurs during idling corresponding to no load.

  Further, in a motor vehicle, even when the wheels are driven at a desired rotational speed by a motor, the driving force transmitted from the driving wheels to the ground changes depending on the ground conditions and the like. For example, when starting on an icy road surface, the wheel slips, but almost no driving force is transmitted from the slipping wheel to the road surface. That is, when the wheel slips, the wheel idles in an unloaded state. For this reason, when a superconducting motor including a plurality of windings connected in parallel or a plurality of coils connected in parallel is employed as a driving source of an automobile, the coil is driven when a wheel slip occurs. A biased current that does not become a force flows. Therefore, not only the efficiency of the motor is greatly reduced, but also the energy stored in the battery is unnecessarily consumed.

  It is an object of the present invention to provide a superconducting motor control system capable of preventing the occurrence of unnecessary AC loss due to drift and improving the efficiency of the superconducting motor in an apparatus such as an automobile to which the superconducting motor is applied. And

The invention described in claim 1 of the present application is a control system for a superconducting motor,
The superconducting motor includes a coil in which a plurality of windings are wound in parallel, or a plurality of coils connected in parallel, and an idling detection unit that detects idling of the superconducting motor, and an idling detection unit And a control means capable of controlling the current value for driving the superconducting motor according to the output.

  The present invention reduces unnecessary AC loss due to the occurrence of a large drift by preventing the superconducting motor from rotating, i.e., idling. In the case where a coil constituted by winding a plurality of windings connected in parallel to one iron core (teeth portion) is provided, the drift occurs between the windings connected in parallel. Moreover, it arises also when the coils provided in the some iron core (tooth part) are connected in parallel, ie, between the coils set to the same phase.

  In the present invention, idling detection means for detecting idling of the superconducting motor is provided. The idling refers to a state in which the motor is rotating at a high speed without a required proper output in a mechanical apparatus or the like to which the superconducting motor according to the present invention is applied.

  In a manufacturing machine or the like that requires a predetermined driving force, the apparatus may be operated even when no workpiece is present. For example, it is conceivable that a hammer is operated despite the absence of a workpiece in a forging machine. In such a case, the superconducting motor rotates without a load, and only unnecessary AC loss increases.

  Also, in an electric vehicle, when the accelerator is depressed on a frozen road surface and the wheel slips, no driving force is generated, and it can be said that the motor is idling. In this case, the driver steps on the accelerator to increase the value of the current flowing through the motor and increase the speed. On the other hand, the wheel is slipping (idling), so it rotates in an unloaded state. Only significant AC loss increases. For this reason, the efficiency of the superconducting motor is greatly reduced.

  In the present invention, the idling detection means for detecting the idling state of the superconducting motor as described above is provided. The control means controls the value of the current flowing through the superconducting motor in accordance with the presence / absence or degree of idling. Specifically, when the idling as described above occurs, the control unit lowers the current value or stops the current. In particular, in the case of an automobile, the value of the current flowing through the superconducting motor is reduced according to the idling rate (slip rate) by using the control device, thereby reducing the rotational speed of the wheel. When the rotational speed of the wheel is lowered, the frictional force between the wheel and the ground increases, so that the idling phenomenon is eliminated and unnecessary AC loss is reduced.

  As the idling detection means, various means can be adopted according to the mechanical device to which the superconducting motor is applied.

  When a superconducting motor is applied to an automobile, idling can be detected using various methods.

  For example, a vehicle body speed detection sensor for detecting the vehicle body speed and a rotational speed detection sensor for driving wheels can be provided to detect the vehicle body speed and the wheel speed, and to detect idling from the difference therebetween.

  Further, when the present invention is applied to a motor for driving an automobile as in the invention described in claim 2, the idling rate detecting means is provided with a rotation speed detecting sensor provided for each of the driving wheel and the driven wheel. It can comprise and can determine idling from the difference of the rotational speed of a driving wheel and a driven wheel.

  Further, as in the invention described in claim 3, the idling detection means includes a rotation speed detection sensor provided on the drive wheel and a torque detection sensor for detecting torque acting on the drive wheel. Can do.

  For example, if the generated torque is small or no torque is generated even though the wheel is rotating at a predetermined rotation speed, it can be determined that the wheel is idling due to slipping or the like.

  According to a fourth aspect of the present invention, the idling detection means includes a phase difference detection device that detects a phase difference between a current change and a voltage change of a drive power supply means (such as an inverter) that drives the superconducting motor. Is.

  When a load is applied from the mechanical device to the superconducting motor, a phase difference occurs between current and voltage as an inverter output serving as drive power supply means. On the other hand, when there is no phase difference, the superconducting motor is driven in a state where the load is not acting, and idling occurs.

  When the phase difference is detected and there is no phase difference or when the phase difference is smaller than a predetermined value, the AC loss can be reduced by reducing the current value flowing to the superconducting motor or stopping the current.

  In an industrial machine, for example, in a forging line, if a hammer is operating when no workpiece is present, the superconducting motor will run idle, causing excessive current to flow, increasing unnecessary AC loss, and reducing the coil. Temperature rises above a predetermined temperature. In such a case, AC loss can be significantly reduced by detecting the presence or absence of a workpiece and reducing the value of the current flowing through the superconducting motor or stopping the current flow.

  The invention described in claim 5 is configured such that the control means controls the output of the cooling means based on the output from the idling detection means.

  As described above, when idling occurs and unnecessary AC loss increases, the amount of heat generated by the coil also increases, which may hinder the superconducting state of the coil. In particular, when the superconducting motor is idling, a large AC loss occurs and the amount of heat generated by the coil is large.

  In the present invention, the calorific value is predicted from the output of the idling detection means, and the output of the cooling means is controlled. That is, by detecting idling, it is possible to detect abnormal heat generation of the device at an early stage. By detecting the heat generation and controlling the output of the cooling means, it is possible to prevent an abnormal temperature rise of the coil.

  In addition, the said control means can also be comprised so that the output of the said cooling means may be controlled in consideration of the output of the temperature detection means which detects the temperature of a coil or a refrigerant | coolant. Further, the cooling means can be controlled in combination with the output from the other idling detection means to prevent the coil temperature from rising.

  The generation of unnecessary AC loss in the superconducting motor can be prevented, and the efficiency of the motor can be increased.

1 is a block diagram according to a first embodiment of a superconducting motor control system according to the present invention. FIG. It is a block diagram at the time of applying the superconducting motor control system of this invention to an electric vehicle. It is a flowchart which shows an example of the control performed with the control system shown in FIG.

  Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows an example of a block diagram when the superconducting motor drive system according to the present invention is applied to a general machine.

  As shown in FIG. 1, a superconducting motor control system 100 according to this embodiment includes a superconducting motor 1, a mechanical device (load) 2 driven by the superconducting motor 1, and a predetermined current applied to the superconducting motor 1. The motor drive power supply means 3 for flowing, the control means 4 for controlling the motor drive power supply means 3, and the cooling means 5 for cooling the superconducting motor 1 are provided.

  As the superconducting motor 1, various forms driven by an alternating current can be adopted. For example, a synchronous motor can be employed.

  As the superconducting coil constituting the superconducting motor 1, those formed from various superconducting materials can be adopted. For example, a superconducting motor including a coil formed from a Bi (bismuth) -based or Y (yttrium) -based oxide superconducting material can be employed.

The configuration of the coil is not particularly limited. For example, a superconducting motor including a coil configured by winding a plurality of windings connected in parallel can be employed. A superconducting motor configured by connecting coils provided in a plurality of iron cores (tooth portions) in parallel can be employed.

  The superconducting motor 1 is provided with a sensor S1 constituting an idling detection means. As the sensor S1 provided in the superconducting motor 1, a rotational speed sensor that detects the rotational speed of the superconducting motor can be employed.

  The mechanical device 2 according to the present invention is not particularly limited. For example, a drive mechanism of an industrial machine such as a machine tool or a drive mechanism of an electric vehicle can be employed.

  The mechanical device 2 can also be provided with a sensor S2 that constitutes an idling detection means. As the sensor S2, a torque sensor for detecting a load or a rotation speed sensor can be employed.

  The motor drive power supply means 3 converts power supplied from a power source (not shown) into motor drive power. For example, when a DC power source such as a battery is used, an inverter is used. The inverter generates an alternating current that drives a superconducting motor from a direct-current power source that includes a battery, and various inverters can be employed.

  The motor drive power supply means 3 can also be provided with a detection device S3 that constitutes an idling detection means. For example, when an inverter is employed as the motor drive power supply means 3, a phase difference detection device that detects the phase difference between the voltage and current applied to the superconducting motor 1 can be provided on the output side of the inverter. When a load is applied from the mechanical device 2 to the superconducting motor 1, a phase difference occurs between current and voltage as the output of the inverter. On the other hand, when there is no phase difference, the superconducting motor is driven in a state where no load is applied. Therefore, idling of the superconducting motor 1 can be detected by providing the detection device S3 that detects the phase difference.

  The control means 4 is for controlling the output of the motor drive power supply means 3, and controls the voltage value, current value, frequency, etc. supplied from the motor drive power supply means 3 to the superconducting motor 1. Thus, the rotational speed and output torque of the superconducting motor 1 are controlled as necessary. As the control means 4, a semiconductor control circuit including a microcomputer can be employed. Control is performed using the control means 4 so as to prevent the superconducting motor 1 from slipping and to be in an optimum operating state.

  The cooling means 5 is for holding the coil of the superconducting motor 1 in a superconducting state, and includes, for example, liquid nitrogen as a refrigerant and a refrigerator for cooling the refrigerant. The cooling means is preferably provided with a refrigerant temperature sensor S4 to monitor the refrigerant temperature.

  In the present invention, the idling detection related device 6 for detecting idling of the superconducting motor 1 can be employed. For example, in a machine tool or the like, a mechanical device related to a pre-process of a machining process that employs a superconducting motor can be employed as the idling detection related device 6. A mechanical device that performs a pre-process of the process performed by the mechanical device can be employed as the idling detection related device 6, and a sensor S5 that detects the presence or absence of a workpiece in the idling detection related device 6 can be employed as the idling detection means. By detecting that the workpiece does not exist in the previous process, it is possible to detect in advance that the superconducting motor 1 is idling.

  The operating means 7 is used when starting the superconducting motor 1 or changing the motor output. For example, when applied to an automobile, an accelerator pedal corresponds to this.

  In this embodiment, in addition to the conventional motor control, the idling of the superconducting motor 1 is detected, and the current value is mainly controlled. Various sensors or detection devices S1 to S5 can be employed depending on the applied mechanical device. The sensors S1 to S3 or the detection device S5 can constitute the idling detection means alone or in combination.

  The idling detection means detects whether or not an appropriate output is generated from the superconducting motor with respect to a predetermined output generated from the mechanical device 2. In a machine tool or the like, only the presence or absence of idling can be detected, and control can be performed so that no current flows when idling occurs. Further, in an electric vehicle or the like, it is preferable to detect the presence or absence of idling with respect to the rotational output of the superconducting motor and increase or decrease the value of the current flowing through the superconducting motor.

  FIG. 2 shows a block diagram when the superconducting motor control system according to the present invention is applied to an electric vehicle.

  The control system 200 in the electric vehicle includes a superconducting motor 1, a driving wheel 2 driven by the superconducting motor 1, motor driving power supply means 3 for supplying driving power to the superconducting motor 1, and the motor driving power supply means. 3, a secondary battery 8 that supplies power to the motor 3, a refrigerator 5 as a cooling means for cooling the superconducting motor 1, and a refrigerator drive that supplies driving power to the refrigerator 5 using the secondary battery as a power source Power supply means 9. An inverter is employed as the motor drive power supply means 3.

  In the present embodiment, as the idling detection means for detecting idling, the rotational speed detection sensor S2 of the driving wheel and the phase difference between the output side current and voltage of the inverter constituting the motor drive power supply means 3 are detected. / V phase difference detection device S3 and rotational speed detection sensor S5 of the driven wheel are used.

  Since the driven wheel is rotated according to the speed of the vehicle body, the traveling speed of the vehicle body can be detected by the rotation speed detection sensor S5 of the driven wheel. Therefore, the presence / absence and degree of idling can be detected by obtaining a comparison value of the rotation speed obtained from the output of the rotation speed detection sensor S2 of the drive wheel 2 and the rotation speed detection sensor S5 of the driven wheel 6.

  Furthermore, in an electric vehicle, it is desirable to reflect the information input from the accelerator pedal 7 as the input means 7 in the control of the superconducting motor. That is, in an automobile, the driver tries to change the speed according to the road surface condition or the like. On the other hand, in a state where slip occurs, even if the number of rotations of the motor is increased, it does not become a driving force, but only an AC loss increases. In such a case, it is preferable to perform control so as to decrease the rotation speed of the wheel by reducing the value of the current flowing through the superconducting motor, contrary to the driver's input information (acceleration instruction by the accelerator pedal).

  The control means 4 controls the motor drive power supply means 3 and the refrigerator drive power supply means 9 based on information from the sensors, and controls the outputs of the superconducting motor 1 and the refrigerator 5 and the like.

  Hereinafter, based on FIG. 3, the control procedure in the control system 200 of the superconducting motor in the electric vehicle shown in FIG. 2 will be described.

  When the ignition switch is turned on (IG ON), the refrigerator 5 is first started (S101). Then, the coil temperature of the superconducting motor 1 is measured by the coil temperature sensor S1 (S102), and it is determined whether or not the coil is below the superconducting critical temperature (S103). When the coil temperature is higher than the superconducting critical temperature (NO in S103), the output of the refrigerator 5 is increased by the control means 4 (S104), and the coil is cooled until it becomes the superconducting critical temperature or less.

  When the coil temperature is equal to or lower than the superconducting critical temperature (YES in S103), a motor drive current is output (S106) in response to an output command from the accelerator pedal 7 or the like (S105). After the superconducting motor 1 is started, the outputs of the various sensors S1, S2, S3, S5 constituting the idling detection means described above are detected (S107).

  The presence / absence of idling is calculated based on each sensor output (S108). For example, in an electric vehicle, the idling detection means can be constituted by the rotational speed sensor S2 of the driving wheel and the rotational speed sensor S5 of the driven wheel, and the idling ratio (slip ratio) can be calculated from the outputs of these sensors. (S108).

  Next, it is determined whether or not to change the current value supplied to the superconducting motor 1 depending on the presence or absence of idling (S109). In order to make the above determination, for example, the control means 4 stores an appropriate rotational speed difference when a predetermined load is applied, and compares the calculated rotational speed difference with the appropriate rotational speed difference. Thus, it can be configured to determine whether or not to change the value of the current flowing through the superconducting motor.

  When it is determined that the current value needs to be changed (YES in S109), the control unit 4 increases or decreases the drive current of the superconducting motor 1 by increasing or decreasing the current value generated from the motor drive power supply unit 3. . If the determined rotational speed difference is larger than the appropriate value, the value of the current flowing through the superconducting motor 1 is reduced or the supply of power is stopped. Thereby, unnecessary AC loss is eliminated and the efficiency of the superconducting motor 1 is improved. Further, in the electric vehicle, unnecessary consumption of the secondary battery 8 can be prevented.

  On the other hand, if it is determined that there is no need to change the current value (NO in S109), various sensor outputs are detected again, whether or not idling is determined, whether or not the drive current needs to be changed is determined, and the drive current Is changed. The loop of the control process is preferably performed at a predetermined time interval after determining whether or not the driving of the superconducting motor 1 is stopped (S111) and unless the driving of the apparatus is stopped (NO in S111). (S102 to S110).

  In this embodiment, in addition to the control for increasing / decreasing the current value of the superconducting motor 1, the refrigerator 5 for cooling the superconducting motor 1 is controlled.

  That is, the value of the AC loss is obtained from the calculation of the presence / absence of idling (S108), the current, voltage, and motor rotation speed applied to the coil, and the amount of heat generated in the coil is predicted (S121).

  If it is determined that the amount of generated heat deviates from the appropriate range and the output of the refrigerator 5 needs to be changed (YES in S122), the output of the refrigerator 5 is changed (S123). For example, when the calculated calorific value is larger than the appropriate range, control is performed so as to increase the output of the refrigerator 5. Thereby, the abnormal temperature rise of a coil is prevented. That is, abnormal heating of the coil can be detected or predicted at an early stage, and unnecessary increase in AC loss can be prevented in advance.

  On the other hand, if it is determined that there is no need to change the output of the refrigerator 5 (NO in S122), the various sensor outputs are detected again (S107) in the same manner as the motor drive current control described above, and the idling of Presence / absence is calculated (S108), calorific value is predicted (S121), it is determined whether or not the output of the refrigerator 5 needs to be changed (S122), and the cooling device output is changed as necessary (S123). The loop of the control process is also preferably performed at a predetermined time interval.

  In the present embodiment, the temperature of the coil of the superconducting motor 1 is directly measured by the temperature sensor. However, the temperature of the refrigerant of the refrigerator can also be measured.

  Further, as the idling detection means, the rotational speed sensor S2 of the driving wheel 2 and the rotational speed sensor S5 of the driven wheel 6 are adopted, but instead of the rotational speed sensor of the driven wheel, a torque sensor of the driving wheel is provided, and the driving wheel 2 It can also be configured to determine that idling has occurred when no torque is generated despite rotation.

  The scope of the present invention is not limited to the embodiment described above. The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined not by the above-mentioned meaning but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  Unnecessary AC loss in the superconducting motor can be reduced and the efficiency can be increased.

DESCRIPTION OF SYMBOLS 100 Control system 1 Superconducting motor 2 Mechanical device S1 Idling detection means (coil temperature detection sensor)
S2 idling detection means (drive wheel rotation speed detection sensor)
S3 idling detection means (power / voltage phase difference detection device)
S5 idling detection means (driven wheel rotation speed detection sensor)
4 Control means 5 Cooling means (refrigerator)

Claims (5)

A superconducting motor control system,
The superconducting motor includes a coil wound with a plurality of windings connected in parallel, or a plurality of coils connected in parallel,
A slip detection means for detecting slipping of the superconducting motor;
A control system for a superconducting motor, comprising: control means capable of controlling a current value for driving the superconducting motor according to an output of the idling detection means. The superconducting motor is a motor for driving an automobile,
2. The superconducting motor control system according to claim 1, wherein the idling detection unit includes a rotation speed detection sensor provided on each of the driving wheel and the driven wheel. The superconducting motor is a motor for driving an automobile,
2. The superconducting motor control system according to claim 1, wherein the idling detection unit includes a rotation speed detection sensor provided on the drive wheel and a torque detection sensor that detects torque acting on the drive wheel. 3.   4. The idling detection unit includes a phase difference detection device that detects a phase difference between a current change and a voltage change of a driving power supply unit that drives the superconducting motor. Superconducting motor control system. A cooling means for circulating the refrigerant to cool the coil,
The control system for a superconducting motor according to any one of claims 1 to 4, wherein the control means controls the output of the cooling means based on the output from the idling detection means.

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